This paper is a continuation of a series of works, devoted to various aspects of the June 30, 1908 Tunguska event. In those days, various sky optical anomalies were observed over a large area. In the presented paper, the main focus is on bright nights. Bright nights are the glow (airglow) of the night sky, visible to the naked eye. In the author's opinion, atmospheric gravitational waves played a large role in their appearance in 1908, as evidenced by the behavior of atmospheric pressure in late June and early July 1908. Some other geophysical peculiarities of that period, which could have affected the appearance of bright nights, and possibly other optical sky anomalies, are also considered.